1. Field of the Invention
This invention relates generally to sheet accumulators and more particularly to an improved accumulator mechanism and an improved method for selectively "under" or "over" accumulating into stacks or passing-through seriatim-fed sheets, the accumulator employing selectively retractable ramp means.
2. Prior Art and Other Considerations
Various accumulators have been employed for accumulation into stacks of sheet material such as paper sheets, documents, and the like. Such uses particularly occur during preparation and processing of mailable articles when a plurality of sheets needs to be assembled into a packet for further handling that may include additional collating, folding, inserting, etc.
For instance, Luperti et al discloses in U.S. Pat. No. 4,805,891 a standard and reverse collator for stacking sheets of paper fed in seriatim thereto from a singulating feeder in the same or reverse order as the sheets appear in the singulating feeder. Sheets are fed between moving endless, elastic belts, ride over a ramp guide, and are thusly delivered over or under prior sheets that have been stopped against a registration device. Adjustment of the location of the ramp guide provides for delivery over or under prior sheets. The registration device is movable to release an accumulated stack of sheets for farther transport after a desired number of sheets has accumulated. Another example of an accumulator that relies on a ramp guide mechanism is disclosed by Golicz in U.S. Pat. Nos. 4,799,663; 4,925,362; and 4,925,180. Reference is made also to co-pending U.S. patent application Ser. No. 746,622 (now U.S. Pat. No. 5,147,092), commonly assigned herewith and entitled "Roller-Accumulator for Sheets".
Whereas prior art accumulators are in many ways not unsatisfactory, high-volume sheet processing imposes requirements upon flexibility and speed of adaptability of the equipment to vary some of its functions. Such variability includes quick and easy adaptability to optionally "over" or "under" accumulate and to optionally pass-through sheets without accumulation into stacks. The retractable-ramp accumulator of the present invention provides such variability.
Accordingly, an important overall feature of the invention is the provision of an improved accumulator and an improved method for the accumulation into stacks of a number of seriatim-fed sheets. The improvements include quick and easy adaptability to optionally "over" or "under" accumulate and to optionally pass-through sheets without accumulation into stacks.